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Your input is important to us. Please provide your valuable feedback. Here are some testimonials from our clients:


It took me less than 10 minutes to put the ECU back in- going very slow.
I drove the car about 50 miles yesterday. I didn't notice anything out of the ordinary when I started out, just casual driving. Which was great because I was worried about warning lights or some problems.

Then I drove it hard the rest of the trip. I don't think you guys are over estimating with the 669hp. The car is a rocket now. I had no trouble with any lights or temperatures either and it was 87 degrees out.

This is by far the best modification I have made to any vehicle in my 20 years of doing so.

The only problem I have is keeping the sunroof shade closed and the tires hooked.

Thanks again,

Ken S.

2012 Mercedes CLS 63 Biturbo (C218)
Posted By: RENNtech

Again I would like to thank you and the entire RENNtech team for a great job on my runs fantastic and I am thrilled. I can't tell you how much I enjoyed the tour of your facility...very impressive...also please tell Hartmut how much I enjoyed chatting with him and looking at adapting my exhaust....hard to find anyone who can knows as much about Formula 1 as he it.

Phil M.

2003 SL600
Posted By: RENNtech

I must admit, living 5 min from Renntech is addictive, could you please move further away.

Renntech has done 6 cars of mine with your modifications.
2012 CLS 63
2012 E 550 4matic
2010 E63.
2009 C63
2007 S 550
2003 E55

I will be doing more mod's to the CLS 63 and I am waiting for the new S series.
Enough said.

Karl M.
Posted By: RENNtech
Hi Bob,

Made it back to Houston. The car worked perfectly. I hope that continues for the next few years.

Please thank the RENNtech team for taking time for me on Monday.
Please be sure to thank Harmut for me as well. I really enjoyed the facility tour and his explanation of the technology.

Thanks for the tee shirt. I will wear it with pride.

Brian L.

2011 Mercedes S65 (W221)
Posted By: RENNtech

Wanted to let you know that the tune is done, and the car feels incredibly fast. I plan on putting it on a dyno shortly, but it is a monster!!! Amazing result, I could not be happier.

I will share the final HP and TQ results.



2012 CLS 550
Posted By: RENNtech
I really wanted to thank everyone at Renntech, especially George for his professionalism and patience in explaining the process.

These guys turned my 2012 cls 550 biturbo into a rocket by just upgrading the ECU.

530 + HP ,603 + FT/LB
0-60: 3.4sec
1/4mile: 11.3 @ 125mph

Sounds good to me.The car is even faster than my 2009 911 twin turbo!!

Thank you again guys.

Dr. Farzad H.

2012 CLS 550 (C218)
Posted By: RENNtech

I got enough of a run to the motorway to heat the engine before opening it up and initial feel was fierce, I actually spun the wheels with kick down it at 90mph, that is just incredible. Now I have the car performance that I was after when I bought the 63! Keeping my eyes peeled on the motorway for anyone brave enough to have a go.. ;)



2012 CLS 63 Biturbo (C218)
Posted By: RENNtech

Everyone at the shop is more than pleased with the end result of everything done to the car. I just wanted to say thank you for all of the support through this. The car is very smooth and powerful throughout all of its gears and drives just like it should. I'm certain that the customer will be very pleased.

Thanks again,

Gil M.

VAST Performance

2006 SL 600 (R230)
Posted By: RENNtech

Definitely more pull and revs are higher between shifts....I need something to throw down on to feel the difference better. Think I will troll for Mustangs and Camaros this evening and work my up to the exotics.....LOL

BIG Thanks Leon!

Dave M

Vehicle: S 65 (W 221)
Posted By: RENNtech
Dear Leon,

I recently ordered your C74 aero package and installed it successfully on my 2010 C63 AMG. The result is nothing short of spectacular, and I am extremely pleased! I want to thank you and your company for producing a superb product.

Gary Z.

2010 C63 AMG + Full C74 Areo Package
Posted By: RENNtech

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7825 SW Ellipse Way, Stuart, FL 34997
(+1) 561 - 845 7888
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7825 SW Ellipse Way - Stuart, FL 34997
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